Long-term COVID-19 effects on pulmonary function, exercise capacity, and health status

BACKGROUND: The long-term effects of respiratory function and related physiological characteristics of coronavirus disease 2019 (COVID-19) survivors have not yet been studied in depth. OBJECTIVE: To examine pulmonary function, exercise capacity, and health-related quality of life among COVID-19 survivors. METHODS: Eighty-five survivors with confirmed COVID-19 were evaluated at the end of 3 and 6 months after disease onset. The assessment included lung function, diffusing capacity, 6-min walk distance (6MWD), and health status by the 36-item Short-Form General Health Survey (SF-36) questionnaire. RESULTS: Totally 85 survivors, 48 (56.5%) were men. The mean (standard deviation) age was 34.6 (9.9) years. Thirteen patients (15.2%) had medical co-morbidities the mean length of hospitalization was 18.5 (5.6) days. 25 (29.4%) required intensive care unit admission, whereas 6 (7%) of them required invasive mechanical ventilation. No significant differences were observed between lung volume parameters. At 6 months, there was a significant reduction in diffusing capacity for carbon monoxide (DLCO), P = 0.02*. 25 (29.4%) of patients had impaired DLCO ≤80% predicted. Regarding 6MWD, a significant increase was noted in 6MWD from 486 ± 72 m at 3 months to 526 ± 82 m at 6 months (P = 0.001*). The 6MWD was lower than that for normal controls of the same age groups. There was significant impairment of health status assessed by SF-36 questionnaire among COVID-19 survivors at 6 months as compared with controls of the same age groups. There were significant positive correlations between lung function parameters (FVC, VC, FEV1, and DlCO) with several SF-36 domains. CONCLUSION: In discharged survivors with COVID-19, 23.5% had significant impairment of diffusion capacity abnormality of lung function. The exercise capacity and health status were considerably lower than that of a normal population after 6 months postinfection.